This invention relates to detergent compositions and in particular to detergent compositions adapted for fabric washing. More specifically, the detergent compositions of this invention provide unexpectedly good detergency performance on greasy and oily soils.
Cationic surfactants have been frequently incorporated into detergent compositions of various types. However, the inclusion of such cationic surfactants is generally for the purpose of providing some adjunct fabric care benefit, and not for the purpose of cleaning. For example, certain cationic surfactants have been included in detergent compositions for the purpose of yielding a germicidal or sanitization benefit to washed surfaces, as is disclosed in U.S. Pat. No. 2,742,434, Kopp, issued Apr. 17, 1956; U.S. Pat. No. 3,539,520, Cantor et al, issued Nov. 10, 1970; and U.S. Pat. No. 3,965,026, Lancz, issued June 22, 1976. Other cationic surfactants, such as ditallowdimethylammonium chloride, have been included in detergent compositions for the purpose of yielding a fabric-softening benefit, as disclosed in U.S. Pat. No. 3,644,203, Lamberti et al, issued Feb. 22, 1972. Such components are also disclosed as being included in detergent compositions for the purpose of controlling static, as well as softening laundered fabrics, in U.S. Pat. No. 3,951,879, Wixon, issued Apr. 20, 1976; and U.S. Pat. No. 3,595,157, Inamorato, issued May 25, 1976.
Compositions comprising mixtures of anionic, cationic and nonionic surfactants are also known in the art. Thus compositions conferring enhanced antistatic character to textiles washed therewith are described in British Pat. No. 873,214 while compositions having enhanced germicidal and detergency performance are disclosed in British Pat. No. 641,297.
European Patent Application No. 78 200 050.9 also describes detergent compositions comprising a specific mixture of anionic, cationic and nonionic surfactants, the compositions being characterized by excellent grease and oil removal characteristics. Nevertheless, these compositions are still found, in practice, to be deficient in a number of areas of performance. Of particular importance is the fact that the level of grease and oil detergency benefits provided by these compositions is sensitive to the concentration of free hardness ions present on the wash liquor. It follows that the compositions are of somewhat lower value when used in the absence of builder, or when used with a builder but in underbuilt conditions (i.e. at a builder/hardness ratio of less than 1), or when the builder is present in a different phase to the hardness ions and acts only slowly to reduce the concentration of hardness ions in solution. The latter situation applies when certain water-insoluble ion-exchanging materials are used as the detergent builder.
In addition, it has also been found that detergent compositions based on long chain alkyl trimethyl quaternary ammonium salts as the cationic tend to degrade during spray drying as a result of the high temperature and pH conditions found in the spray drying tower. This can lead to such compositions aquiring unacceptable odour characteristics.
It has now been found that mixtures of specific anionic, nonionic and alkoxylated cationic surfactants in critical relative amounts provide yet further improvements in cleaning performance on greasy and oily soils, these improvements being observed at both high and low wash temperature and over a range of realistic polar and nonpolar greasy soil types and surprisingly over a range of hardness conditions and builder types. Furthermore, the enhanced greasy stain removal performance is achieved without detriment either to detergency performance on conventional soil and stain types or to the soil suspending characteristics of the composition.
The use of alkoxylated cationic surfactants in detergent and textile treatment compositions is not new of course. For instance, British Pat. Nos. 1,234,092, 1,301,909, 1,330,873, 1,014,887, U.S. Pat. No. 3,959,157 and Japanese Application No. 50-135434 all variously disclose the use of ethoxylated cationic surfactants in textile treatment, shampoo or liquid detergent applications. It would appear, however, that there has been no recognition hitherto of the grease and oil removal performance advantages of detergent compositions based on alkoxylated cationic surfactants, nor has there been any disclosure of the formulation parameters now found to be critical for determining detergency performance on grease and oil stains.
The invention thus provides detergent compositions having improved detergency performance on grease and oil stains; compositions whose detergency performance is less sensitive to free hardness in the detergent liquor, or to the identity of the builder present in the formulation; and compositions having improved physical characteristics, especially odour characteristics, when prepared by spray drying.